Backless electrical control panel box

ABSTRACT

A electrical control panel enclosure or box characterized by the absence of a back. Instead of being used as the conventional subpanel, the control panel, when attached, becomes the back panel of the control box. In making the attachment, an air space is maintained between the control box sides and the control panel so that air can enter the control box to reduce its ambient operating temperature. To maintain the strength of the backless control box, its sides are of channel construction. The control box is useful as a general electrical control box as well as in conjunction with electrical resistance duct heaters.

[4 1 Aug. 1, 1972 [54] BACKLESS ELECTRICAL CONTROL PANEL BOX [72]Inventor: Rolf G. Albers, St. Louis, Mo.

[73] Assignee: Brasch Manufacturing Company, Inc., St. Louis, Mo.

[22] Filed: Oct. 5, 1970 [21] Appl. No.: 77,870

[52] US. Cl ..3l7/100, 317/120, 174/50 R [51] Int. Cl. ..H02b 1/08, H05k5/02 [58] Field of Search.....174/l6 R, 50 R, 52 R, 53, 57; 312/223,242, 245, 255, 278; 317/99, 100, 104,105,107,111,120,121

[56] References Cited UNITED STATES PATENTS 3,142,003 7/1964 Olashaw..l74/52 R 3,210,456 10/1965 Skubal ....174/52 R 3,299,199 1/1967Mattingly ..174/50 3,201,656 8/1965 Houck ..31 7/120 X 3,075,487 l/l963Appleton ..174/50 3,360,752 12/1967 Uptegraff 1 74/52 X PrimaryExaminer-Lewis H. Myers Assistant Examiner-Gerald P. TolinAtt0rneySidney B. Ring 57 I ABSTRACT A electrical control panelenclosure or box characterized by the absence of a back. Instead ofbeing used as the conventional sub-panel, the control panel, whenattached, becomes the back panel of the control box. In making theattachment, an air space is maintained between the control box sides andthe control panel so that air can enter the control box to reduce itsambient operating temperature. To maintain the strength of the backlesscontrol box, its sides are of channel construction. The control box isuseful as a general electrical control box as well as in conjunctionwith electrical resistance duct heaters.

2 Claims, 2 Drawing Figures PATENTEDAUS 1 1912 SHEEI 2 BF 2 01 6. ALGEesI nvvewrog 2 F7 7702 5 BACKLESS ELECTRICAL CONTROL PANEL BOX Thisinvention relates to a control panel enclosure or box. More particularlythis invention relates to a control panel enclosure adapted to beemployed in conjunction with electrical resistance duct heaters.

In recent years forced air heating has become quite popular. Its use hasbeen accelerated by the fact that an air conditioning system-can alsouse the same ducts as the forced air heating system. Furthermore, withthe advent of low cost electricity and better engineering andinsulation, the use of forced air electric heat has become increasinglypopular. The simplicity of the design and use of resistance electricheating units plus the fact that they can be installed economically in aplurality of places in the duct system with individual controls hasaccelerated the trend.

Examples of electric duct heaters are described in the following PatentApplications: Ser. No. 879,309, now U.S. Pat. No. 3,622,752, Ser. No.879,310 now abandoned, and Ser. No. 879,412, now US. Pat. No. 3,613,525,all filed on Nov. 24, 1969.

In these patent applications the control box containing the controlpanel is directly wired into the duct heater terminal box. However, incertain instances where this is impractical or undesirable remotecontrol boxes containing control panels are installed. This is oftentrue of large installations. Such control panels are often extremelylarge and may contain controls for one or more heaters some for examplehaving heights and/or widths of from about 1 to feet or more.

Heretofore control panel enclosures, such as those employed forelectrical duct resistant heaters, have been of the box type, i.e. a boxwith a door. Their total construction comprises a back, four sides and adoor. The control panel board which contains the controls issuperimposed on and attached to the back to form a sub-panel and thedoor is shut so as to enclose the control system. The control box ishung in a suitable place such as on a wall.

Because the control panel is enclosed in a box, heat created within thebox during operation is not easily dissipated so that heat build upoften damages the electrical components. Therefore, it is desirable toconstruct a control box which is capable of dissipating the heat createdso as to reduce the ambient temperature of the box.

In addition, it is desirable to be able to construct a control box whichwould employ less metal without sacrificing strength thus reducing theweight and cost thereof.

I have now devised a control box which is capable of dissipating heat soas to reduce the ambient temperature within the box. In addition I haveachieved this by employing a control box which employs less metalwithout sacrificing the strength thereof thus reducing the weight andcost thereof.

The invention is best understood in connection with the drawings whereFIG.. 1 is a cut-away perspective view of a control box of thisinvention.

FIG. 2 is side sectional view of FIG. 1 cut along line A 13 A.

The control box comprises four sides 1,2,3,4 made of channel metal, suchas steel, and a front door. The control box has no back. The channelmetal sides are constructed so that the door 5 can fit on the front andthe control panel 6 on the rear. By having no back, metal is saved inthe construction of the control box since in normal construction thecontrol panel is merely superimposed upon the back of the control box asa subpanel thus adding to the weight and cost thereof. Thus, theomission of the back results in economies of metal, weight and cost.

In positioning the control panel into its proper position in the controlbox, an air space or gap is maintained through which air can circulateinto the control box so as to reduce its ambient temperature thusassisting in the proper operation of the control panel and reducingdamage to the electrical components.

The air space is obtained by employing spacing means, such as byemploying spacing nut 8 and attaching nut 8. The size of 8 is selectedso as to produce the desired air space or gap. By positioning spacingnut 8 in sufficient places between the control panel and the channelsides designed to receive them, a desired air space 7 is obtained. Thepoints of attachment of the control panel to the channel sides willgenerally number 4 or more by employing spacing nut 8 which serves adual function in conjunction with 8' as both a spacing and fasteningmeans. Heat generated by the controls rises to the top of the box andexits therefrom as cooler air is drawn into the control box through airspace 7 thus reducing the ambient temperature. Because of the deviouspath through which air must travel in order to enter the box, the dangerof hot metal splattering (in case of electrical failure) outside the boxis substantially eliminated. The presence of any openings in the controlbox without such a devious path would pose a safety problem. The essenceof the present invention is the presence of air openings without thehazard of allowing hot metals or other hazardous materials to be thrownout of the box so as to result in a fire hazard such as might occur witha direct as contrasted to the indirect air space opening of the presentinvention.

Normally a control box is mounted directly against the wall. In thepresent invention in order to insure the flow of air, the control box ismounted so that a space is maintained between the wall and the controlbox. This is achieved by any suitable spacing and/or mounting devices. Asuitable device comprises special mounting feet 9, l0, 1 1 (the fourthfoot not shown) with an offset bend which automatically spaces thecontrol box away from the wall thus allowing air to enter the spacebehind to control box and subsequently through the air space 7.

Since no back is employed in the construction of the control box itself,some means must be employed to strengthen the backless box. This isachieved by em ploying channel construction of the metal sides.

The term channel construction as employed herein means that the sidesare not a straight length of metal but are bent at various angles toeach other, generally at right angles to each other so as to create achannel. In the present specific embodiment the channel construction hasthe following configuration as seen from the side view:

I r v 1 The main channel is shown in dark lines and the lips which areadded for convenience of attachment and enclosure are shown as dottedlines.

Thus, in the present embodiment, the front of the side is bent at 12 toreceive the door 5, which continues along the front until it reaches thesides; then it is bent to form the sides; then bent again at the back toform part of the back; then bent again into the bottom side of thecontrol box; and then bent again to form surface 13 where the controlpanel 6 can be positioned. In the particular embodiment these bends aregenerally at right angles to each other. Besides using the bends toimpart strength, they also create positions which are designed toreceive other components of the overall construction, such as in thepresent instance the front door and the control panel. By proper designthe bend of the other components, such as the bend of the door 14 andthe bend of the control panel 15, are designed to form lips whichoverlap such as to avoid a direct exit to the outside of the controlbox, thus avoiding hot metal splattering outside the box in case ofoverheating.

The control box is constructed in a simple manner. Metal of the properguage such as 16 guage is bent into the desired channel pattern and cutto the proper length to create the sides of the control box. Thesechannel sheets are then welded to each other at substantially rightangles to form the sides of the control box. Hinges (not shown) are thenplaced in the front of these sides and the door attached thereto.I-Ioles are drilled into the back lip of the channel sides and thecorresponding section of the control panel which are joined 'by screwsand nuts with spacing nuts between the back lip and the control panel.Mounting feet with an offset bend are welded to the back of thechanneled metal.

The size of the particular control box will vary with the particularsystem, for example having a height and/or width of from 1 to feet ormore. By employing the present invention ambient operating temperaturereductions have been achieved. For example, by employing a Iii-inch airspace and mounting feet with a Ki-inch off-set bend, in temperaturetests performed by comparing the ambient temperatures within the presentcontrol box to the ambient temperature with a corresponding box ofconventional construction, the present construction maintains lowertemperatures within the enclosure. In practice, a temperature drop ofabout 20F. has been obtained.

In addition despite the absence of a back, the configuration of thechannel sides which forms the enclosure itself is such that greatstrength is achieved so that smaller guage inetal can be employed andstill be stronger than control boxes conventionally made. For example,if desired, the conventional metal guag'e of M can be reduced to 16, andin certain instances even lower, without sacrificing strength.

This invention can be used a control panel enclosure or box for generalapplications as well as for use in conjunction with electricalresistance duct heaters. Since electrical connections and controldevices are conventional, there are none shown in the drawings.

When used with electrical resistance duct heater the control panelenclosed in the control box may include some, or all, of the followingfeatures, plus others:

a. main electrical connections b. fuses c. magnetic or mercurycontactors d. transformers e. control terminals f. fan interlock relaysg. disconnect switches h. toggle switches i. pneumatic electric switchesj. fused or non-fused disconnects k. pilot lights I. pilot switches m.step controls n. SCR controls, etc.

Although the invention has been described by making detailed referenceto a currently preferred embodiment, this should be understood solely inan instructive,

rather than limiting, numerous variations being contemplated as withinthe scope and spirit of this invention.

Having thus described my invention what I claim as new and desire toobtain by Letters Patent is 1. An electrical control panel box fordissipating heat created therein to reduce the ambient temperature ofsaid box and for preventing hot metals or other hazardous materials frombeing thrown out of said box upon overheating, said box having channelsides, a door and a control panel forming the back thereof, said controlpanel being operatively attached to and spaced from said channel sidesforming therebetween devious air space for allowing air to circulatethrough said box without the need of any air openings in and through anyof said sides, door and control panel.

2. The electrical control panel box of claim 1 wherein said controlpanel is inserted within said channel sides to form the back thereof,whereby said air space is formed between said control panel and saidchannel sides.

1. An eleCtrical control panel box for dissipating heat created therein to reduce the ambient temperature of said box and for preventing hot metals or other hazardous materials from being thrown out of said box upon overheating, said box having channel sides, a door and a control panel forming the back thereof, said control panel being operatively attached to and spaced from said channel sides forming therebetween devious air space for allowing air to circulate through said box without the need of any air openings in and through any of said sides, door and control panel.
 2. The electrical control panel box of claim 1 wherein said control panel is inserted within said channel sides to form the back thereof, whereby said air space is formed between said control panel and said channel sides. 